Vertical axis wind turbines, or VAWT's, are known for use in power generation and water pumping applications. Savonius wind turbines are one type of vertical-axis wind turbine, used for converting the power of the wind into torque on a rotating shaft. They were invented by the Finnish engineer Sigurd J Savonius in 1922. Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-type devices. Because they are drag-type devices, Savonius turbines extract much less of the wind's power than other similarly-sized lift-type turbines. Reported power coefficients for Savonius turbines vary from about 0.15 to about 0.30.
Another type of VAWT that combines both lift and drag characteristics is described in the following U.S. Pat. Nos. 4,359,311; 4,715,776; 4,784,568; 4,830,570; 4,838,757; and, 5,494,507, all to Alvin Benesh. The turbine that is described in these patents is an improvement over typical Savonius style turbines, but still includes room for improvements in efficiency and manufacturing.
There is therefore a need for further improvements in vertical axis wind turbines.